Authentication certificates, such as cards and passports, are known to have a configuration in which a relief layer that exhibits optical effects, such as diffraction, is sandwiched between two laminate materials that form the outer shape of the authentication certificate.
When such an authentication certificate is produced, a transfer foil including a relief layer is first prepared, and the relief layer is bonded to a first laminate material. Subsequently, a second laminate material is stacked on the first laminate material, and the two laminate materials and the relief layer are then pressed while heating to thereby fuse the two laminate materials together. Thus, a security laminate obtained by integrating a laminate can be used as an authentication certificate (see, for example, PTL 1).
Compared with when a relief layer is transferred to a laminate material, when two laminate materials are fused together, it is necessary to maintain a state in which the laminate is heated to a higher temperature, or in which higher pressure is applied to the laminate, over a longer period of time. Therefore, compared with a relief layer positioned on the surface of the security laminate, a relief layer positioned in the inside of the security laminate is required to have a higher melting point and higher rigidity so that the relief layer is prevented from being damaged or deformed to the extent that the optical effects of the relief layer are affected.